Problem: The sum of two numbers is $28$, and their difference is $4$. What are the two numbers?
Solution: Let $x$ be the first number, and let $y$ be the second number. The system of equations is: ${x+y = 28}$ ${x-y = 4}$ Solve for $x$ and $y$ using elimination. Add the top and bottom equations together. $ 2x = 32 $ $ x = \dfrac{32}{2} $ ${x = 16}$ Now that you know ${x = 16}$ , plug it back into $ {x+y = 28}$ to find $y$ ${(16)}{ + y = 28}$ ${y = 12}$ You can also plug ${x = 16}$ into $ {x-y = 4}$ and get the same answer for $y$ ${(16)}{ - y = 4}$ ${y = 12}$ Therefore, the larger number is $16$, and the smaller number is $12$.